The 2007 Mars Smart Lander Mission Science Definition Team (SDT), chartered by
NASA Headquarters in April 2001, was given the task of defining and prioritizing the
science goals, objectives, investigations, and measurements associated with this landed
opportunity. In addition, the SDT was asked to consider: (a) the extent to which
meeting science objectives associated with the 2007 mission should depend on
precursor measurements such as those expected from the planned Mars Reconnaissance
Orbiter (MRO), (b) whether or not direct life detection experiments should be
attempted, (c) the extent to which the mission should be used for technology
development and testing to help prepare for Mars Sample Return, and (d) the
importance of radioisotope power sources (RPS) for meeting mission objectives. For
reference, Appendix 1 provides the detailed SDT Charter, Appendix 2 lists SDT
Membership, and Appendix 3 is a summary of the tasks that led to generation of this
report.

The report is structured in the following way: An overview of the main aspects of
the Mars Smart Lander Mission is first presented to set the stage for consideration of
science opportunities. Next, specific science objectives are defined that are of highest
priority and well matched to the mission objectives. Two options for surface science are
then delineated, followed by detailed scenario analyses that demonstrate that the
options are credible. The report closes with specific recommendations associated with
programmatic issues and a concluding statement.

2.0 Overview of Smart Lander Mission

The Mars 2007 Smart Lander Mission will feature a precision landing capability to
get to within approximately 5 km of a given target site. This capability will allow
landing in any of a large number of relatively safe places that are in close proximity to
rougher areas of very high scientific interest. In addition, a terminal hazard detection
and avoidance system will be used to select safe areas within the landing ellipse,
thereby allowing a landing to occur in more hazardous terrain than possible before the
2007 opportunity. Touchdown robustness will also be enhanced by judicious hardening
of landed systems using appropriate technologies. Landing site altitudes will need to
be less than +2.5 km above the MOLA-derived zero elevation of Mars. These
capabilities in total will allow delivery of approximately 1620 kg (820 kg for landing
systems; 800 kg for surface systems, including approximately 70 to 100 kg of science
payload) of landed assets in 2007 with a much wider selection of locations than
possible, for example, with the 2003 Mars Exploration Rover (MER) landing system.

Launch, transfer, and arrival constraints associated with the 2007 opportunity,
combined with the payload mass, dictate use of a Delta IV or Atlas V launch vehicle and
an arrival subsolar longitude of approximately 130 degrees (northern summer). Direct
entry will be used to place assets on the surface. For solar-powered systems the range
of latitudes for surface operations will be limited to approximately 30 degrees about the
equator. The mission lifetime and operational activities will also be highly modulated
by seasonal controls on amount of sunlight. On the other hand, use of RPS power
systems would allow access to all locations on the planet below the altitude cutoff, with
an extended period of operations. A primary mission duration of 180 sols is assumed
for solar-powered missions and 360 sols for RPS-powered systems. It is noted that RPS
systems could easily provide steady power for up to 720 sols, but that the total cost of
the mission would need to increase significantly to accommodate flight systems
designed to operate over such a long period of time.

These main characteristics of the Smart Lander Mission were the background for the
SDT deliberations. The job of the SDT was to make recommendations focused on
science to be accomplished during this landed opportunity and the payloads needed to
accomplish the science, and to comment on topics specifically requested in the SDT
Charter (Appendix 1). The Smart Lander precision landing, coupled with delivery of a
large payload to the surface, offers an opportunity to conduct science on an
unprecedented scale on Mars. The SDT looked at this opportunity to define the Smart
Lander Mission as the capstone mission for this decade by making groundbreaking
scientific discoveries and paving the way for the sample return mission.

The Mars Exploration Payload Analysis Group (MEPAG) has developed a
comprehensive strategic plan for exploration of Mars that is focused on the overarching
goals of understanding whether or not life got started and evolved, the causes and
timing of current and past climates, and the nature and extent of resources available at
and beneath the surface [Greeley, 2000]. The role and availability of water is a central
theme. Further, a full understanding of life, climate, and resources requires detailed
study of the evolution of the interior, surface, and atmosphere, along with the interplay
of various cycles (e.g., climatic and tectonic) that may have dominated Mars during past
epochs. All of these results impact our understanding of the extent to which surface
and near-surface materials can be used to support human expeditions and the extent to
which humans need to cope with hazards during their missions.

The MEPAG document was the starting point for SDT deliberations. That is, the
goals, objectives, investigations, and measurements defined by MEPAG were
scrutinized for applicability to the Smart Lander Mission, refined and updated as
needed, and used to form the backbone of the science to be accomplished during the
2007 landed opportunity. What follows in this section is a discussion of the science
objectives that can be addressed for each of the Mars Exploration ProgramÕs main
themes, which are: development and evolution of life, current and past climates,
evolution of the surface and interior, and preparation for human expeditions.